i am from pakistan and have multipale business visa of china ..can i get japanese one in bejing?

I am afraid that you may not apply for it at Japanese embassy in Beijing. According to the embassy, foreigners from the third countries can apply for Japanese visas at Japanese embassy in Beijing unless they hold Chinese Z type one. And they need to apply for it from Beijing Municipal People's Government Foreign Affairs Office entry-exit personnel service center.

You may contact the embassy for more information.